books.google.com - The enormous genetic flexibility of bacteria jeopardizes the usefulness of currently available antibiotics, and requires new approaches to antibiotic discovery and development. Antimicrobial resistance can be acquired in a short time frame, both by genetic mutation and by direct transfer of resistance...http://books.google.com/books/about/Bacterial_Resistance_to_Antimicrobials_S.html?id=QSqEWjAptjcC&q=Streptococcus+pneumoniae&utm_source=gb-gplus-shareBacterial Resistance to Antimicrobials, Second Edition